Intestinal absorption of zinc declines significantly with age, dropping by approximately half.
"where they used stable isotopes of zinc... And they found that basically, as you age, your ability to absorb zinc across your intestine drops significantly um by about half." (said at 0:38:40)
Early metabolic ward studies using stable zinc isotopes (such as 67Zn and 70Zn) specifically reported that fractional zinc absorption dropped by approximately half in elderly subjects compared with young adults (e.g., 17% vs. 31% in Turnlund et al., 1986; 21% vs. 39% on an adequate diet in August et al., 1989). However, this finding is conditional: these studies had very small sample sizes (n = 6 to 9 per group), and subsequent stable-isotope studies in healthy older adults have shown mixed results, including studies where intestinal absorption remained largely preserved depending on diet and health status.
- supports: Determination of zinc and copper absorption at three dietary Zn-Cu ratios by using stable … (The American journal of clinical nutrition 1989)
"Zn absorption on the adequate diet was 39 +/- 3% (means +/- SEM) in young subjects and 21 +/- 1% (p less than 0.05) in the elderly subjects." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Stable isotope studies of zinc absorption and retention in young and elderly men. (The Journal of nutrition 1986)
"Zinc absorption averaged 17% in elderly men, significantly less than average zinc absorption of 31% in young men." (abstract, results, passage verified)
pubmedfull study (doi) - contradicts: Zinc absorption in healthy elderly humans and the effect of diet. (The American journal of clinical nutrition 1993)
"Zinc absorption from the high-bioavailability test meal was not significantly different (P > 0.05) in the young (38.9 +/- 9.8%, mean +/- SD) and elderly (35.0 +/- 10.9%) subjects... Thus, zinc absorption ability seems to be preserved in healthy elderly people, at least until the age of 80 y." (abstract, results)
pubmedfull study (doi)